WHITEHOUSE STATION, N.J., Feb. 8, 2012  Merck (NYSE:MRK), known as MSD outside the United States and Canada, announced today that Thomas E. Shenk,
Ph.D., has decided to retire from its board of directors, effective today. Dr. Shenk is leaving the board to focus on the new company he is forming to commercialize discoveries made in his Princeton University laboratory in the area of
antiviral therapeutics.

Dr. Shenk has been Elkins Professor in the Department of Molecular Biology at Princeton
University since 1984. He served as the departments chairman from 1996 to 2004. Dr. Shenk joined Mercks board in 2001.

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